1. Field of the Invention
This present invention relates to a paper feeding device, and more particularly to a paper feeding device preferably applicable to an office device such as a printer, a copier and a scanner.
2. The Related Art
A conventional paper feeding device is generally used in various office devices such as a printer, a copier, a scanner and the like, it is highly desirable to feed single paper sheet from a stack of paper sheets placed at a paper feeding plate. There are many known prior paper feeding devices for single sheet feeding of paper.
A particular paper feeding device is disclosed in U.S. Pat. No. 5,573,338. In accordance with this patent, the paper feeding device includes a pick roller, a first spring element, a second spring element, a separator pad and a gate. The first spring element and the second spring element are disposed to contact with the pick roller at different positions in the conveying direction of the paper. The gate is provided between the first spring element and the second spring element to suppress the feed of papers. The separator pad is disposed to contact with the pick roller at the downstream side of the second spring element. In operation, the lowermost paper is in contact with the pick roller due to its own weight. As the pick roller rotates, plural pieces of papers will enter between the first spring element and the pick roller. Due to the action of the gate, the lowermost paper and several pieces of papers enter between the second spring element and the pick roller. And then only the lowermost paper can pass through the pick roller and the separator pad.
However, during the process of the paper feeding, the first spring element always presses on the pick roller, so the pick roller is prone to be abraded as the first spring element rubs it too much. In addition, the first spring element presses on the pick roller before the paper feeding device conveying papers to provide a prior press acting on the pick roller. The single paper needs a large enough push force to push the first spring element to insert between the first spring element and the pick roller, so when the push force acting on the single paper is not large enough, the paper feeding of single paper will be false.